The Rainbow City of Dreams, also more properly known as Borealis, is the capital city of the galaxy. It was originally intended to be built on a planet called Prismiria, but when the planet suffered a sudden existence failure in a supercharged field of theta particles, the city disappeared with all its new inhabitants inside.
The city now pops in and out of existence at completely random times, but the nonexistence time is always too short to notice- less than a millisecond. Every time it reappears into existence, it is somewhere else, on a completely different planet. This happens once every three or so days.
The residents of the RCOD are just as rainbow as the city they live in; however, they're very dowdy folk, to tell the truth. Most of them are wrees and wreas.